Chemotherapy extravasation injury refers to the accidental leakage of cytotoxic drugs from a vein into the surrounding tissue. This complication can lead to severe local injury, including tissue necrosis in some cases, and is therefore considered a medical emergency requiring prompt recognition and intervention.

Risk factors for extravasation include cannula placement into small, tortuous, or fragile veins, placement into a vein in a limb that has previously undergone radiation or chemotherapy, or the presence of an impaired venous circulation, lymphedema, Raynaud phenomenon, diabetes (type 1, type 2), or obesity. The degree of immunocompetence may modulate both the clinical severity of extravasation injuries and the therapeutic response to their management.

Cytotoxic agents are classified according to their potential to induce tissue damage if infiltration occurs. Neutrals, such as asparaginase and cyclophosphamide, typically do not cause any tissue reaction. Exfoliants, such as cisplatin and docetaxel, can lead to skin exfoliation. Inflammatory agents, such as methotrexate and fluorouracil, mainly trigger inflammation and discomfort without extensive tissue destruction. Irritants, such as carboplatin and etoposide, generate pain and local irritation. Vesicants are most destructive to tissue and may cause necrosis and ulceration with subsequent potential for nerve, muscle, ligament, and bone injury.

The extent of tissue injury from a vesicant depends on further factors, including the drug's concentration, the extravasated volume, the duration of exposure, and its ability to bind to DNA. Vesicants that bind to DNA, such as the anthracyclines (ie, doxorubicin), mitomycin, and mechlormetamine, have the greatest potential for tissue damage, as they affect replicating cells. Non-DNA-binding vesicants include vincristine, vinblastine, and vinorelbine (the vinca alkaloids). The anatomic sites at greatest risk for permanent damage from a vesicant include areas with scant subcutaneous tissue and a thinner dermis, such as the dorsal hands and feet, the antecubital fossae, and the ankles.